Tuesday, 17 April 2018
Champions DEFGH (Sawgrass Marriott)
Ocean-Waves-Atmosphere (OWA) exchanges are not well represented in current Numerical Weather Prediction (NWP) systems, which can lead to large uncertainties in tropical cyclone track and intensity forecasts. In order to explore and better understand the impact of OWA interactions on tropical cyclone modelling, a fully coupled OWA system based on the atmospheric model Meso-NH, the oceanic model CROCO and the wave model WaveWatch3 was designed and applied to the case of intense tropical cyclone Bejisa, which passed nearby Reunion Island (SW Indian Ocean) in January 2014.
The fully coupled OWA simulation shows good agreement with the literature and available observations. In particular, simulated significant wave height is within 30 cm of measurements made with buoys and altimeters. Sensitivity experiments used to highlight the impact of oceanic waves show that waves have limited impact on the track, the intensity evolution and the turbulent surface fluxes of the tropical cyclone. However, it is shown that using a fully coupled OWA system is essential to obtain consistent sea salt emissions and to properly reproduce their impact on heat and momentum fluxes.
The fully coupled OWA simulation shows good agreement with the literature and available observations. In particular, simulated significant wave height is within 30 cm of measurements made with buoys and altimeters. Sensitivity experiments used to highlight the impact of oceanic waves show that waves have limited impact on the track, the intensity evolution and the turbulent surface fluxes of the tropical cyclone. However, it is shown that using a fully coupled OWA system is essential to obtain consistent sea salt emissions and to properly reproduce their impact on heat and momentum fluxes.
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